1. Technical Field
The present invention relates to inspection apparatuses, particularly to a visual inspection apparatus for flexible printed circuit boards.
2. Description of Related Art
Currently, flexible printed circuit boards can be manufactured using a roll-to-roll process which is a substitute of a typical sheet-by-sheet process. In the roll-to-roll process, a number of flexible printed circuit board units are manufactured using a copper clad substrate successively. The copper clad substrate is fabricated into the flexible printed circuit board units in a manner such that the copper clad substrate is wound up around a number of rollers to be performed a series of processes for manufacturing flexible printed circuit boards.
Generally, in the roll-to-roll process, after vias and electrical traces of each of the flexible printed circuit board units are fabricated, the vias and electrical traces of each of the flexible printed circuit board units are required to go under inspection so as to ensure the quality of the vias and electrical traces. Nowadays, an inspection process for inspecting the vias and electrical traces of each of the flexible printed circuit board units can be performed using an automatic optical inspection system or a manual visual inspection system.
However, the automatic optical inspection system is very expensive which greatly increases the overall cost of manufacturing flexible printed circuit boards. Currently, to save cost, the flexible printed circuit board (e.g., the copper clad substrate that has been fabricated into a number of flexible printed circuit board units) is generally inspected manually using the manual visual inspection system. However, a roller of the manual visual inspection system is generally driven to roll by a single motor. In the inspection process, the motor starts and stops frequently. When the motor starts, the flexible printed circuit board is pulled and a tension occurring on the flexible printed circuit board is large. When the motor stops, a tension occurring on the flexible printed circuit board disappears suddenly and the flexible printed circuit board is wrapped over the roller. Thus, the tension acts on the flexible printed circuit board is changed frequently, thereby damaging the electrical traces of the flexible printed circuit board. As a result, quality of each of the flexible printed circuit board units manufactured is inferior.
What is needed, therefore, is a visual inspection apparatus for inspecting the flexible printed circuit board by manually in a roll-to-roll process of manufacturing flexible printed circuit boards, thereby balancing the tension the flexible printed circuit board in the roll-to-roll process, and preventing the flexible printed circuit board from being damaged.